Impact of intensity and loss assessment following the great Wenchuan Earthquake

The great Wenchuan Earthquake occurred on May 12, 2008 in the Sichuan Province of China, and had a magnitude of 8.0. It is the most serious earthquake disaster in China since the great Tangshan Earthquake （Ms=7.8, July 28, 1976）. According to official reports, there were 69,225 deaths, 379,640 injuries and 17,939 missing as of Aug. 11, 2008. The China Earthquake Administration quickly sent hundreds of experts to the field immediately after the event, to investigate the damage and assess the economic losses. This paper emphasizes the impact of seismic intensity and presents a preliminary loss assessment. A brief description of the geological features of the affected region is provided, followed by a summary of the earthquake damage. An isoseismal map is developed that shows that the high intensity region is distributed like a belt around the seimogenic fault, and that the epicentral intensity reached Ⅺ （Chinese Intensity Scale, similar to the Modified Mercalli Scale）. The direct economic loss resulting from the earthquake is 692 billions RMB （about 100 billions US$）.

Integrating RS technology into a GIS-based earthquake prevention and disaster reduction system for earthquake damage evaluation

This paper presents a method to integrate remote sensing （RS） data processing, generation of isoseismal lines and human-computer interaction modules into an improved GIS-based disaster reduction system. Using the RS data processing module, a statistical sample gray value and the RS-intensity at each field survey point in the region are calculated from the probabilistic relationship between the RS-variable and earthquake intensity, and stored in the GIS-based system database. Then, isoseismal lines are generated by a trend surface model from RS-intensity. They are further improved via modification of the isoseismal lines based on the empirical attenuation relationship calculated by using the RS-variable in the human-computer interaction module. The field survey shows that the proposed method gives a good generation of isoseismic lines. As a result, the accuracy of the damage and loss evaluation and the efficiency of the emergency decision making capability are improved.

South Segment of Minjiang Fault and Diexi Earthquake in 1933

Diexi earthquake(M7.5)in 1933 is a great event that occurred at the east border of Qinghai- Xizang Plateau in the 20th century.There are obviously different opinions about the shape ofisoseismal lines and the genetic fault of this earthquke.Based on the study of the newlyfound north-south trending active fault and ground fissures of Diexi earthquake,this papertends to hold that,as the southward extension of Miujiang fault,this north-south trendingactive fault might be the genetic fault of this event.

Relationship between Modified Mercalli Intensity and peak ground acceleration in Myanmar

In this study, the previously reported isoseismal maps are compiled and used to carefully investigate the macroseismic intensity in terms of the Modified Mercalli Intensity (MMI) scale, based on the engineering ground-motion parameter, as the peak ground acceleration (PGA), inferred from the ground-motion attenuation characteristic of Myanmar. The preliminary relationship between the MMI and PGA is reported to be a function of log10(PGA) = 0.2526MMI – 3.1006. The strongly correlated MMI-PGA relationship obtained in this study, if confirmed, will be particularly useful in real-time applications for damage prediction or engineering parameter determination when an earthquake occurs in or nearby to Myanmar. Compared with the previously proposed MMI-PGA relationships for other regions, the standard of building construction in Myanmar is not high enough to withstand the hazards from earthquakes, particularly at higher levels of ground motion. Therefore, the standard building code for Myanmar should be modified in order to reduce future hazards arising from earthquakes.

Seismic intensity investigation of the 2001 M=6.0 Yajiang-Kangding earthquake and discussion on its background of seismogenic structures

An M=6.0 earthquake occurred on February 23, 2001 in the western Sichuan Province, China. The macro seismic epicenter situated in the high mountain-narrow valley region between Yajiang and Kangding counties. According to field investigation in the region, the intensity of epicentral area reached VIII and the areas with intensity VIII, VII and VI are 180 km2, 1 472 km2 and 3 998 km2, respectively. The isoseismals are generally in elliptic shape with major axis trending near N-S direction. The earthquake destroyed many buildings and produced some phenomena of ground failure and mountainous disasters in the area with intensity VIII. This event may be resulted from long-term activities of the Litang fault and Yunongxi fault, two main faults in the western Sichuan. The movements between the main faults made the crust stress adjusted and concentrated, and finally the earthquake on a secondary fault in the block released a quite large energy.